Exposure to 1,2-Propanediol Impacts Early Development of Zebrafish (Danio rerio) and Induces Hyperactivity

The use of electronic cigarettes (e-cigarettes) is increasing as an alternative to tobacco burning cigarettes; however, their safety remains to be fully determined. The long-term effects of e-cigarettes are unknown, including the effects of maternal e-cigarette use on pre- and postnatal development. Additional research on the safety of e-cigarettes is needed. Especially useful would be information from high- and moderate-throughput economic model systems. This study investigates the effects of 1,2-propanediol, which was identified as the main component of e-cigarette liquid, on early development of zebrafish (an in vivo high-throughput model system that was recently proposed for the study of tobacco cigarette and e-cigarette toxicity). Zebrafish embryos were exposed to 1.25% or 2.5% 1,2-propanediol from 6 to 72 h post-fertilization (hpf). We show that exposure to 1,2-propanediol did not significantly affect mortality. Hatching success was significantly lower in 2.5% 1,2-propanediol-exposed embryos at 48 hpf, but at 72 hpf no significant differences were noted. Moreover, exposure to 1,2-propanediol reduced growth and increased the incidence of string heart, pericardial edema, and yolk sac edema. Most importantly, developmental exposure to 1.25% 1,2-propanediol caused hyperactive swimming behavior in larvae. This study demonstrates that 1,2-propanediol has adverse impacts on early development in zebrafish.